hd25-1 ii impedance: 70 or 65 ohms?

Some pages list the impedance of hd25-1 ii as 70 ohms, others as 65 ohms. The photos show hd25-1 with "70 ohms" written on them. The sennheiser webpage says it's 65 ohms.
The headroom graph shows the impedance is above 80 ohms for HD-25

So what is the real impedance of HD25-1 ii and why some claim a different one?

does it matter?

Quote:

Originally Posted by toanaldino

does it really matter it's 65 or 70 ohms?

It really doesn't matter to me and for me there's no difference, I was just puzzled by websites/e-shops (including sennheiser themselves too) claiming 65 ohms in their specs and at the same time having hi-rez photos of HD25-1 with "70 ohms" clearly visible on them. So which one is correct and how did the other number originate and why do they use it?